Abstract: In an optical system having an extremely simple configuration configured by first and second prisms which are prisms in a flat shape and a reflecting surface provided in these prisms, in the first prism which is disposed on a side close to the eyes, that is, on a side apart from a video display element (video element) at a certain distance, a correction lens surface for correcting a chromatic aberration of video light is provided. Accordingly, a virtual image display apparatus is small and light, and has a high performance with a reduced chromatic aberration of magnification.

Abstract: An optical system of a virtual image display apparatus is configured such that, in regard to a width in a first direction and a width in a second direction at a first surface position, and a width in a first direction and a width in a second direction at a second surface position corresponding to the width in the first direction and the width in the second direction at the first surface position, predetermined conditional expressions are established. With this, in an optical system for an HMD which includes a light guide member having a free-form surface, it is possible to allow video light to be emitted toward eyes in an appropriate state while controlling the light guide of video light accurately and maintaining high performance.

Abstract: In first and second display devices that are provided in a pair on the left and right sides, image light and external light are superimposed on each other and viewed. In this case, a parallax of an angle (the value of angle) is set by a frame unit functioning as a parallax setting unit tilting principal rays of left and right image light inwardly, and the angle of convergence of an observer is in an appropriate state in the case of viewing the image light.

Abstract: A light guide member includes four or more curved surfaces including three or more non-axisymmetric curved surfaces so that video light emitted from a video element and passing through the light guide member is displayed to an observer on a divergent optical path in an enlarged manner. Reflection of the video light is made four times by four surfaces different from one another in the inside of the light guide member, such that at least total reflection is performed on a third surface as a second reflection among the four times of reflections, total reflection is performed on a first surface as a third reflection, reflection is performed on a second surface as the fourth reflection, and the video light reaches the eyes of the observer by being transmitted through the first surface.

Abstract: A half mirror layer has an angle dependency in which when an angle of incidence becomes larger than the angle of incidence range of image light, reflectance increases, such that it is possible to prevent unintended light, which is emitted to a light transmitting member from a light guiding member and is reflected inside a light transmitting member, from being returned to a light emission portion of the light guiding member after passing through the half mirror layer as a reflective film at a relatively large angle of incidence. Therefore, it is possible to prevent the image light passed through the light transmitting member from becoming ghost light while mitigating the demand for increasing processing accuracy of the light transmitting member, and bonding accuracy between the light guiding member and the light transmitting member, to provide a high quality virtual image displayed by a virtual image display device.

Abstract: A chemically and thermally stable phosphor having unconventional light emitting properties and high light emitting intensity with an LED of 470 nm or less, includes an inorganic compound comprising: a crystal designated by A3(D,E)8X14, a crystal designated by Sr3Si8O4N10 or an inorganic crystal having the identical crystal structure of the Sr3Si8O4N10 crystal, which comprises A element, D element, X element, and optionally E element if necessary (A is one or more kinds selected from Li, Mg, Ca, Sr, and Ba; D is one or more kinds selected from Si, Ge, Sn, Ti, Zr, and Hf; X is one or more kinds selected from O, N, and F; and E is one or more kinds selected from B, Al, Ga, In, Sc, Y, and La.), into which M element is solid-solved (M is one or more kinds selected from Mn, Ce, Pr, Nd, Sm, Eu, Tb, Dy, and Yb.).

Abstract: In an image generation unit, a light emitting part is formed using a self-emitting OLED device, and thereby, high-contrast images can be formed and the life of the light emitting part and the life of the virtual image display apparatus are extended. Even when the light emitted in the light emitting part has deviation in color balance, a half-mirror layer that has light transmissivity and realizes see-through vision is a reflection film having wavelength dependence, and thereby, a uniform color balance of image lights is achieved and images in good conditions are visually recognized.

Abstract: Principal rays of component lights output from a periphery side of respective positions of an image surface generated in an image generation unit forming an image display device are controlled in an intensity distribution control unit so that the principal rays may be inclined more largely toward a center optical axis side than principal rays of component lights output from a center side and output, control is performed so that lights are output in the strongest intensity distributions with respect to axial directions of the principal rays of the respective component lights of image lights output in the respective positions by the intensity distribution control unit, and further, the positions can be adjusted by adjustment of output angles of the respective component lights in response to an aspect ratio of the image surface.

Abstract: imagelight and outside light are viewed to overlap in a half mirror layer which is a semi-transmissive reflection unit from a state in which a polarization property of the outside light is canceled by a depolarization member disposed more outside than a light-guiding region of the imagelight.

Abstract: In a battery pack, an overcharge detecting circuit compares a voltage between a positive electrode and a negative electrode of a secondary battery with a threshold voltage to detect an overcharge of the secondary battery, and turns off a switching element. A series circuit including a thermistor and a resistor is arranged near the secondary battery and connected in parallel to the secondary battery. A comparator compares a voltage at a junction point of the thermistor and the resistor with a reference voltage corresponding to a predetermined temperature. In response to an output signal of the comparator, a changing unit changes the threshold voltage to a first value when a temperature of the secondary battery is below the predetermined temperature, and changes the threshold voltage to a second smaller value when the temperature of the secondary battery is above the predetermined temperature.

Abstract: An intermediate image is formed inside a prism by a projection lens and the like. Image light, totally reflected, in the order of a third surface, a first surface and a second surface, on two or more surfaces thereof, reaches an eye of an observer after passing through the first surface. Thus, it is possible to decrease the thickness of the prism and to reduce the size and weight of the entire optical system. Further, it is possible to realize a bright high-performance display with a wide viewing angle. With respect to external light, it is possible to pass the external light through the first surface and the third surface, for example, for observation. Further, by setting diopter at this time to about 0, it is possible to reduce defocusing or warp of the external light when the external light is observed in a see-through manner.

Abstract: A video monitoring system has a monitor device that displays a video captured by a camera and a map containing a plurality of camera icons. The camera icons on the map are selected in sequence by an operator and cameras corresponding to the camera icons are used for generating a video display in the monitor device. A split screen partition count is made for the monitor device in accordance with the selected camera icon count; and a monitor video signal is generated on the basis of the cameras that have been selected.

Abstract: A half mirror layer has an angle dependency in which when an angle of incidence becomes larger than the angle of incidence range of image light, reflectance increases, such that it is possible to prevent unintended light, which is emitted to a light transmitting member from a light guiding member and is reflected inside a light transmitting member, from being returned to a light emission portion of the light guiding member after passing through the half mirror layer as a reflective film at a relatively large angle of incidence. Therefore, it is possible to prevent the image light passed through the light transmitting member from becoming ghost light while mitigating the demand for increasing processing accuracy of the light transmitting member, and bonding accuracy between the light guiding member and the light transmitting member, and thereby it is possible to make a virtual image displayed by a virtual image display device have a high quality.

Abstract: A secondary battery protection circuit for protecting a secondary battery including: a power supply terminal; a protection operation circuit configured to monitor a state of the secondary battery through the power supply terminal to generate a signal for turning on/off conduction of a current path between the secondary battery and a load according to a protection state determined by the monitored state of the secondary battery; a nonvolatile memory in which data is written by a writing voltage being provided at the power supply terminal, an operation of the secondary battery protection circuit being controlled by the data; a voltage generation circuit configured to generate a provision voltage which is provided to a low withstand voltage circuit; and a control circuit configured to enable the nonvolatile memory to store the data therein in accordance with the protection state upon an input voltage being greater than a determination threshold voltage.

Abstract: An image display device includes a display unit that displays an image so as to be visually recognized by an observer, a holding member that holds the display unit and has at least a portion thereof exposed to the outside, and a heat conduction member, having a sheet shape, which is connected to the holding member. The display unit includes an image forming device that forms the image. The heat conduction member comes into contact with the image forming device so as to be capable of heat conduction, and transmits heat of the image forming device to the holding member.

Abstract: A light guide member (10) includes three surfaces of a second surface (S12), a fourth surface (S14), and a fifth surface (S15) as two or more non-axisymmetric curved surfaces, and a projection lens (30) includes a lens surface (31a) as a non-axisymmetric aspheric surface. With this, on the light guide member side, even when there is a shape constraint that the first surface (S11) or the third surface (S13) which is a surface contributing to light guide is a flat surface, and correction of asymmetric aberration is limited, it becomes possible to perform sufficient aberration correction as the whole of an optical system including the projection lens. Therefore, the virtual image display apparatus can have a wide viewing angle and high performance, and can be made small and lightweight.

Abstract: Provided is a chemically and thermally stable phosphor having different emission characteristics than the conventional phosphor and exhibiting high emission intensity if combined with an LED of 470 nm or less. The phosphor of the present invention is represented by a composition formula: MdAeDfEgXh (d+e+f+g+h=1; M is one or more kinds of elements selected from Mn, Ce, Pr, Nd, Sm, Eu, Tb, Dy, and Yb; A is one or more kinds of elements selected from Mg, Ca, Sr, and Ba; D is one or more kinds of elements selected from Si, Ge, Sn, Ti, Zr, and Hf; E is one or more kinds of elements selected from B, Al, Ga, In, Sc, Y, and La; and X is one or more kinds of elements selected from O, N, and F) and parameters d, e, f, g, and h satisfy the predetermined condition.

Abstract: A battery protection circuit for protecting a secondary battery, the battery protection circuit not having a CPU, includes a non-volatile memory into which characteristics data determining protective characteristics of the battery protection circuit are writable; and a protection operation circuit which performs a protection operation of the secondary battery based on the characteristics data read out of the non-volatile memory.

Abstract: An image relay optical system is provided with an optical coupling member before incidence of image light on a light guide member. Among a first light incident surface, a coupling member reflecting surface, and a first light emitting surface provided in the optical coupling member, the coupling member reflecting surface and the first light emitting surface are curved surfaces. Therefore, a large bright virtual image with reduced aberration can be displayed.

Abstract: A phosphor having different light emission characteristics from the conventional phosphor, having high emission intensity and chemical and thermal stability, combined with LED of less than 450 nm. This phosphor includes an inorganic compound comprising: a crystal represented by Ba1Si4Al3N9, an inorganic crystal having the same crystal structure as Ba1Si4Al3N9 crystal, or a solid solution crystal thereof, comprising A element, D element, E element, and X element (A is one or more elements selected from Li, Mg, Ca, Sr, Ba, and La; D is one or more elements selected from Si, Ge, Sn, Ti, Zr, and Hf; E is one or more elements selected from B, Al, Ga, In, Sc, and Y; X is one or more elements selected from O, N, and F), into which M element is solid-solved (M is one or more elements selected from Mn, Ce, Pr, Nd, Sm, Eu, Tb, Dy, and Yb).